Optical displays have been getting smaller, slimmer, and more advanced by the second, but we doubt any are as pared down as the ones created by Finnish scientists from nothing but air and water. Based out of Aalto University, the researchers took their inspiration from the superhydrophobic properties of the lotus leaf, whose ability to repel water led the team to create an optical information display that shows writing using water. Read on to learn more about this fascinating example of biomimicry.

When a lotus leaf’s surface is immersed in water, a trapped air layer covers the entire surface allowing it to simply roll off. The Aalto team, led by Dr. Robin Ras, took the leaf’s dual-structured water-repelling surface as their inspiration and fabricated a surface with structures in two size scales: microposts that have a size of ten micrometers and tiny nanofilaments that are grown on the posts.

This two-level surface allowed the air layer to exist in two different shapes, or wetting states, while corresponding to the two size scales. The team also found that they could easily switch between the two states locally using a nozzle to create over- or under-pressure in the water.

In layman’s terms, the surface became a bistable reflective display allowing Ras and his team to draw on the underwater surface with a water jet just like an Etch-A-Sketch. Yet when they took the surface out of the water, it was completely dry and no writing was visible.

“This result represents the first step in making non-wettable surfaces a platform for storing or even processing information,” said academy professor Olli Ikkala. In theory, this could lead to the creation of televisions that are primarily based on water!